A stain-resistant coating material as disclosed in Patent Document 1 has been conventionally known. This stain-resistant coating material is a mixture of a first agent and a second agent. The first agent is an article obtained by preparing a perfluoroalkyl group-containing organosilicon compound and a hydrolysable group-containing methylpolysiloxane compound, and co-hydrolyzing these compounds in a hydrophilic solvent including 0.1 N aqueous hydrochloric acid solution, t-butanol and hexane. The second agent is a mixture of an organopolysiloxane and methanesulfonic acid as a strong acid.
This stain-resistant coating material is considered to be composed of an addition compound in which plural molecules are complicatedly intertwined, or a kind of polymer. When this stain-resistant coating material is applied on the surface of the glaze layer of a sanitary ceramic ware or on the surface of a glass product, a stain-resistant layer is formed as the stain-resistant coating material dries. The stain-resistant layer is bonded to the hydroxyl groups present on the surface of the glaze layer or glass, and shields the hydroxyl groups to make them incompetent. For this reason, even when the sanitary ceramic ware or the glass product is brought into contact with water containing soluble silica, attachment of soluble silica to the hydroxyl groups can be prevented, and attachment of water scale caused by soluble silica is prevented, so that the accumulation of contaminant components on the water scale can be effectively prevented.